Targeting intracranial electrical stimulation to network regions defined within individuals causes network-level effects.

Intracranial electrical stimulation (ES) is routinely used therapeutically, diagnostically, and to provide causal evidence in neuroscience studies. However, our understanding of the brain network-level effects of ES remains limited. We applied precision functional mapping (PFM), based on functional magnetic resonance imaging (fMRI), to define large-scale networks within individual patients with epilepsy. We show that single-pulse electrical stimulation (SPES) and high-frequency electrical stimulation (HFES) are more likely to evoke within-network responses and elicit network-related behavioral effects, respectively, when applied near a PFM-defined network region. Network-level effects were more likely when stimulating sites in white matter, in close proximity to the targeted network, and within a region predominantly occupied by the targeted network. Furthermore, network-specific modulation may be achievable by applying lower current intensities at these sites. Our findings support that modulation of specific networks is achievable by targeting ES to a functional anatomic "sweet spot" that can be identified using PFM.NEW & NOTEWORTHY Precision functional magnetic resonance imaging (fMRI) allows within-individual network definition in patients with epilepsy. Intracranial stimulation effects are aligned with individual-level network topography. Current intensity and proximity to white matter were also critical for effects. Precision fMRI can be used to target stimulation to modulate specific networks.